Ingredients

• 3 tablespoons olive oil
• 6 leeks, light green and white parts, cleaned, finely chopped
• 1/4  teaspoon salt
• Freshly ground pepper
• 3/4 pound dried elbow macaroni
• 1 cup frozen baby peas
• 1/4 pound sliced prosciutto, finely chopped

Sauce

• 3 tablespoons each: unsalted butter, flour
• 3 cups milk, warmed
• 2 cups shredded each: Pepper Jack cheese, sharp Cheddar cheese
• 1/4 cup freshly grated Parmesan cheese
• 1 tablespoon Dijon mustard
• 1/2 teaspoon each: salt, white pepper

Topping

• 1/2 cup panko or other bread crumbs
• 1/4 cup freshly grated Parmesan cheese
• 2 tablespoons unsalted butter, cut into tiny pieces

Instructions

1. Heat the oven to 375 degrees. Heat oil in large non-aluminum skillet on medium-high heat. Add the leeks and cook, stirring often, until caramelized, about 15 minutes. Add salt and pepper to taste.
2. Transfer to a large bowl. Meanwhile, heat a large saucepan of salted water to a boil. Stir in the macaroni; cook until slightly soft to the bite, 7 minutes. Drain. Place in bowl with leeks; toss. Add peas and prosciutto; toss.
3. For sauce, melt the 3 tablespoons butter in the large skillet over medium-low heat. Sprinkle the flour over the butter; whisk to mix well. Cook, stirring, until the flour is absorbed and the mixture is bubbling, about 2 minutes.
4. Stir in the milk gradually; heat to a simmer over medium heat. Cook until the white sauce is smooth and thickened, 3-4 minutes. Add the cheeses. Remove from the heat; whisk constantly until the cheese is completely melted. Stir in the mustard, salt and pepper. Pour over the macaroni leek mixture; mix to combine.
5. Place a greased 8-inch-square baking pan on a baking sheet. Transfer the macaroni mixture to the pan. For the topping, combine the breadcrumbs and Parmesan in a small bowl.
6. Sprinkle evenly over the macaroni. Dot with the butter; bake uncovered, until the top browns and begins to form a crust, 35-40 minutes. Let cool 10 minutes before serving.

Tips

• Use Italian penne or fusilli instead of elbow macaroni
• Substitute blue cheese for the Pepper Jack cheese
• Substitute mortadella or speck for the prosciutto

Advance Preparation

This may be made up to two days ahead, covered and refrigerated. Bring to room temperature before reheating in a 350-degree  oven for 20 minutes. You may need to cover with foil so it does not burn.

Serves 6 people.